如何在golang中以标准方式从http请求获取数据？

Question

I am trying to get the data from http request in golang. I am using net/http package. In my server handler I am trying to get the data from r.Body

body, err := ioutil.ReadAll(r.Body)
if err != nil {
    log.Printf("FATAL IO reader issue %s ", err.Error())
}

it works fine when I curl the service with some input data.

curl --data '{"AppName":"Proline","Properties":null,"Object":"","Timestamp":"2016:03:27 00:08:11"}' -XGET http://localhost:8081/api/services/test/

But when I try to call this service from ajax call r.Body is empty.

requestJSON = '{"AppName":"Proline","Properties":null,"Object":"","Timestamp":"2016:03:27 00:08:11"}'
$.ajax({
  type: "GET",
  url: "http://localhost:8081/api/services/test/",
  data: requestJSON,
  contentType: "application/json; charset=utf-8",
  dataType: "json",
  success: function(data){alert(data);},
  failure: function(errMsg) {
      alert(errMsg);
  }
});

So I changed to read the input data from r.Form

r.ParseForm()
var body []byte
for key, _ := range r.Form {
    body = []byte(key)
    break
}

But now the curl request fails. Is there a standard way to retrieve input data from http request in golang? I am using Go 1.6. Could someone help me with this?

Answer 1

Sending a meaningful body with a GET request is disallowed by the spec. So your browser is probably sending an empty body. You can use POST instead. Its unsurprising that r.ParseForm() is not working because it expects the body to be encoded by application/x-www-form-urlencoded. Not json.

If GET is more appropriate to send the user inputs to your server's request handlers you can use url query parameters.

Quoting JQuery.ajax() docs for data parameter,

Data to be sent to the server. It is converted to a query string, if not already a string. It's appended to the url for GET-requests. See processData option to prevent this automatic processing. Object must be Key/Value pairs.

So you can do,

$.ajax({
  type: "GET",
  url: "http://localhost:8081/api/services/test/",
  data: {AppName: "Proline", Properties:null, Object: ""}, // An object, not a string.
  contentType: "application/json; charset=utf-8",
  dataType: "json",
  success: function(data){alert(data)}
})

An in the server,

params := r.URL.Query()
params.Get('AppName') // returns 'Proline'

See docs: https://golang.org/pkg/net/url/#URL.Query